The Senate’s move to block a series of gun control measures — particularly a proposal expanding background checks — has been viewed as the dagger that destroyed any chance of enacting new firearms restrictions in the wake of December’s grade-school massacre in Newtown, Conn.

But as Washington’s policymakers have shifted their attention to budget issues and immigration reform, gun control groups have used the Senate defeat to redouble their fight for tougher policies that polls show have overwhelming public support.

The advocates are frantically conducting surveys, staging rallies, funding television ads and storming town-hall meetings in an effort to keep the issue in the headlines and to keep the pressure on lawmakers to return to it this year.

“They need to know they have defied the will of the people, and that their cold calculation that there is more intensity on the gun-nut side is wrong,” said Cliff Schecter, a liberal strategist who advocates for tougher gun laws.

“We are in the process of showing them that. And we intend to continue.”

The White House has said only public pressure can inject gun control with new momentum.

“It requires the voices and the participation and the engagement of average Americans,” White House spokesman Jay Carney said Wednesday.

During a speech in Mexico City on Friday, President Obama vowed to "continue to do everything in my power" to pass gun control legislation, saying that it's "the right thing to do."

Obama said he swore an oath to uphold the Second Amendment, and "I always will.” But he said passing legislation to prevent criminals from obtaining guns will "save lives" in both the United States and Mexico.

The first lady said she was struck by the extent to which fear dominated the children's everyday lives. “I mean, every single kid worries about their own death, or the death of someone, every single day,” Michelle Obama said.

The advocates are taking those messages to heart.

“There’s the ground war and the air war and everything in between,” said Dan Gross, president of the Brady Campaign to Prevent Gun Violence. “And it’s all important.”

Ayotte, an opponent of the Manchin-Toomey bill, hosted several town-hall discussions this week at which gun control supporters pointedly challenged her vote against the measure.

On Tuesday in Warren, N.H., the questions came from Erica Lafferty, the daughter of Sandy Hook Elementary School principal Dawn Hochsprung, who was killed in Newtown.

On Thursday in Fitzwilliam, N.H., the pressure came from Gilles Rousseau, whose daughter, Lauren, was a substitute teacher killed at Sandy Hook.

In some ways, the left is using a page from the Tea Party playbook. The strategy of confronting lawmakers at town-hall meetings was used by Tea Party activists when healthcare reform was moving through Congress during President Obama’s first term.

Mark Glaze, director of Mayors Against Illegal Guns, which helped organize those pressure campaigns, said last month’s Senate vote “outraged” voters who thought wide-spread public support for expanded background checks would be enough to get the measure passed. The goal of groups like his, Glaze added, is “to channel” that emotion for the sake of finishing the job — however long it takes.

“Losing a vote on a 90-10 issue has only pissed people off,” Glaze said Thursday, referring to polls that put support for universal background checks around 90 percent. “They’ll go as long as they need to go.”

Town halls are not the only forums the advocates are using. In Washington, gun control supporters staged a rally last week designed to shame gun lobbyists on K Street into dropping their clients.

Gross said the campaign, which initially targeted centrist senators, has now expanded to the House, where the group is urging lawmakers to endorse a companion to the Manchin-Toomey bill. That measure, sponsored by Reps. Mike Thompson (D-Calif.) and Pete King (R-N.Y.), has attracted more than 100 supporters, but House GOP leaders have said they won’t act on gun issues before the Senate does.

Meanwhile, Manchin is trying to tweak his proposal to attract the support of the five additional senators it needs to defeat a filibuster. It’s unclear what changes would go far enough to entice centrist lawmakers to switch their votes.

“That impacts Alaska, but I think we’d still have problems,” Begich had said before last month’s vote. “It’s not going to seal the deal.”

Andrew Arulanandam, spokesman for the National Rifle Association (NRA), which led the opposition to the Manchin-Toomey bill, said this week that Washington policymakers should focus on repairing the “broken” background check system that exists currently for licensed gun dealers before it expands those screenings to include private sellers, as the Manchin-Toomey bill would do.

“We can’t even do the current system right ... and yet they’re talking about expanding it?” Arulanandam said by phone Thursday. “It doesn’t make any sense.”

Arulanandam said the first step should be to repair a “revolving door justice system” that allows prohibited gun buyers and sellers to go free “without serving the proper time.”

“Make sure that those who break the law are arrested, prosecuted and punished,” he said. “That’s the problem.”

Asked if the NRA would support a background check expansion if the current system were fixed, Arulanandam said, “I’m not going deal with hypotheticals.”

Thompson, the California Democrat, said this week that no reforms will move through Congress unless those who support those ideas become more vocal.

“There’s still a lot of folks who will think it’s the law and haven’t been passionately involved, and they need to get passionate,” Thompson said Thursday in an interview with MSNBC. “They need to contact their congressman or woman and tell them to sign up on this bill.”

--This article was originally published at 12:53 p.m. and last updated at 4:26 p.m.